Dual valve reinforced sheath and method

ABSTRACT

A large-diameter expandable sheath for use in introducing a catheter or other medical instrument into a vessel in the body of a patient. The expandable sheath comprises an elongate sheath tube formed of a flexible material which has proximal and distal extremities and a passage extending therethrough of a maximum predetermined diameter. The distal extremity of the elongate sheath tube is folded longitudinally to a smaller folded diameter. The sheath tube may be self-expanding or may be reinforced with a self-expanding wire or expandable stents. A backflow adapter is secured to the proximal extremity of the elongate sheath tube. The backflow adapter has a central opening therein in registration with the passage in the sheath tube. A normally closed primary valve is disposed in the central opening of the backflow adapter and is movable to an open position. A normally open secondary valve, movable to a closed position, may be configured in the backflow adapter proximal the sheath tube and distal the primary valve. The primary and secondary valves when open permit a catheter or other medical instrument to be inserted into the sheath, and when closed form a hemostatic seal about the catheter. A sheath introducer is provided for guiding the distal end of the sheath tube into a vessel and is configured to be positioned within the backflow adapter.

This application is a division of application Ser. No. 08/333,229, filedNov. 2, 1994, now U.S. Pat. No. 5,484,418, which is a division ofapplication Ser. No. 109,131, filed Aug. 19, 1993, now U.S. Pat. No.5,495,349, which is a continuation-in-part of application Ser. No.07/807,089, filed Dec. 13, 1991, now U.S. Pat. No. 5,256,150.

BACKGROUND OF THE INVENTION

This invention relates to an expandable sheath and more particularly toa dual valve, reinforced, large-diameter expandable sheath and method ofuse.

Expandable access catheter assemblies have heretofore been provided tofacilitate the placement and removal of diagnostic and therapeuticcatheters through the vascular system. Such catheter assemblies includeda flexible variable-diameter catheter body, a diameter control stylerand a flexible Y-hub. The flexible Y-hub incorporates an adjustablehemostasis valve and a side port in one branch and a diameter controlstylet guide wire in another branch. A flexible variable diametercatheter body is secured to the flexible Y-hub and can be expandedbetween a collapsed position and an expanded position by the styletguide wire. Several deficiencies have been found in such a device. Forexample, the-adjustable hemostasis valve is incapable of accepting largecatheters. The flexible variable-diameter catheter body is objectionablein that it has a tendency to reduce in diameter and hold ontolarge-diameter catheters when it is attempted to place the same throughthe catheter body. In addition, the tip of the stylet guide wire catchesa large-diameter catheter which causes elongation of the catheter bodyand reduction in its diameter to grab and prevent further advancement ofthe large-diameter catheter. There is therefore a need for a new andimproved large-diameter expandable sheath which will overcome thesedeficiencies.

SUMMARY OF THE INVENTION

The present invention comprises a sheath assembly for use in introducinga catheter or other medical instrument into a corporeal vessel. Thesheath assembly includes an elongate sheath tube formed of a flexiblematerial having proximal and distal extremities and having a passageextending therethrough. The distal extremity of the sheath tube may havea reinforcing means for causing radial expansion of the distal extremityof the sheath tube to an expanded diameter.

The sheath assembly further includes a backflow adapter having a bodywith a central opening in fluid communication with the sheath tube. Thebackflow adapter includes a normally closed primary valve and mayinclude a normally open secondary valve. When the primary and secondaryvalves are open they permit a medical instrument to be inserted intosaid sheath tube and when closed form a hemostatic seal about theinstrument. The sheath assembly may further include a sheath introducercapable of being disposed in the passage of said sheath tube.

The primary valve is disposed proximal the secondary valve. The primaryvalve has a cylindrical member formed of a flexible material having aproximal end and a distal end configured with a bore therein in fluidcommunication with the passage of the sheath tube. The primary valvealso has a ring gear secured to one end of the cylindrical member, arack for driving the ring gear to cause relative rotation between theends of the cylindrical member to cause the cylindrical member to betwisted to close the bore extending through the cylindrical member, andbiasing means for urging the rack into a position wherein thecylindrical member is rotated to a closed position.

The secondary valve is secured to the proximal extremity of the sheathtube, and has a cylindrical member formed of a flexible material havinga proximal end and a distal end configured with a bore therein inregistration with the passage of the sheath tube. The secondary valveincludes rotating means for engaging the cylindrical member for causingrelative rotation between the ends of the cylindrical member to causethe cylindrical member to be twisted to close the bore extending throughthe cylindrical member.

In general, it is an object of the present invention to provide anexpandable sheath which can be utilized with large-diameter cathetersand method for using the same. Another object of the invention is toprovide a sheath of the above character which is folded longitudinallyto a small diameter and which can be expanded greatly when alarge-diameter catheter is to be passed through it. Another object ofthe invention is to provide a sheath of the above character which isprovided with a backflow adapter which includes a tubular diaphragm thatcan be moved into an hourglass or iris-like configuration to create afluid-tight barrier around any tubular device such as a large-diametercatheter passed through the backflow adapter and the tubular diaphragm.Another object of the invention is to provide a sheath of the abovecharacter in which a dilator can be utilized for expanding the sheath.Another object of the invention is to provide a sheath of the abovecharacter in which the backflow adaptor can be readily controlled.

Other features and advantages of the present invention will becomeapparent from the following detailed description, taken in conjunctionwith the accompanying drawings, which illustrate, by way of example, theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a large-diameter expandable sheathassembly incorporating the present invention and in which a sheathintroducer is disposed in the sheath tube.

FIG. 2 is an enlarged side elevational view of the sheath introducershown in the large-diameter expandable sheath assembly of FIG. 1.

FIG. 3 is an enlarged detail view partially in cross-section of thedistal extremity of the sheath introducer shown in FIG. 2.

FIG. 4 is a cross-sectional view taken along the line 4--4 of FIG. 1.

FIG. 5 is a partial side elevational view of an alternative embodimentof an expandable sheath tube incorporating the present invention.

FIG. 6 is a cross-sectional view taken along the line 6--6 of FIG. 5.

FIG. 7 is a cross-sectional view similar to FIG. 4 showing the sheath ofFIGS. 5 and 6.

FIG. 8 is an enlarged side elevational view partially in cross-sectionof the proximal extremity of the large expandable sheath of the sheathassembly shown in FIG. 1 and particularly showing the backflow adapter.

FIG. 9 is an end elevational view looking along the line 9--9 of FIG. 8with certain portions being shown in cross-section and with the valvecarried by the backflow adapter being in a normally closed position.

FIG. 10 is a view similar to FIG. 9, but showing the valve in an openposition.

FIG. 11 is a side elevational view partially in cross section oppositethe side shown in FIG. 8 of the proximal extremity of the expandablesheath.

FIG. 12 is a bottom plan view looking along the line 12--12 of FIG. 11.

FIG. 13 is a top plan view looking along the line 13--13 of FIG. 11.

FIG. 14 is a side elevational view of the valve or diaphragm utilized inthe backflow adapter shown in FIGS. 9 and 10.

FIG. 15 is an alternative embodiment of a valve or diaphragm for use inthe backflow-adapter shown in FIGS. 9 and 10.

FIG. 16 is still another embodiment of a valve or diaphragm for use inthe backflow adapter show in FIGS. 9 and 10.

FIG. 17 is a view similar to FIG. 9 but showing an alternative rack andpinion arrangement for the backflow adapter.

FIG. 18 is a cross-sectional view showing another embodiment of a rackfor the closing and opening of the valve in the backflow adapter.

FIG. 19 is a cross-sectional view taken along the line 19--19 of FIG.18.

FIG. 20 is a side elevational view of an alternative embodiment of thesheath assembly incorporating the present invention and in which asheath introducer is disposed in the sheath tube.

FIG. 21 is an enlarged elevational view partially in cross-section ofthe proximal extremity of the sheath assembly shown in FIG. 20 andparticularly showing the back-flow adapter.

FIG. 22 is a partial side elevational view of an alternative embodimentof an expandable sheath tube incorporating the present invention.

FIG. 23 is a cross-sectional view taken along the line 23--23 of FIG.22.

FIG. 24 is an end elevational view looking along the line 24--24 of FIG.21 with certain portions being shown in cross-section and with theprimary valve being in a normally closed position.

FIG. 25 is a side elevational view partly in cross-section of theprimary valve shown in FIG. 24 in an open position and held by a keeper.

FIG. 26 is an enlarged detailed view partially in cross-section of analternate embodiment of the distal extremity of the sheath tube and thesheath introducer, showing the radiopaque marker band on the introducerand a radiopaque marker on the sheath tube.

FIG. 27 is a partial side elevational view in cross-section of analternate embodiment of an expandable sheath tube incorporating aself-expanding reinforcement means.

FIG. 28 is a partial side elevational view of an alternate embodiment ofan expandable sheath tube incorporating a helical coil.

FIG. 29 is a partial side elevational view in cross-section of analternate embodiment of an expandable sheath tube incorporating ahelical coil embedded between an inner sheath tube and an outer sheathtube.

FIG. 30 is a partial side elevational view in cross-section of analternate embodiment of an expandable sheath tube incorporating stentsand a balloon for expanding the stents.

FIG. 31 is a partial side elevational view of an alternate embodiment ofan expandable sheath tube incorporating U-shaped expandable wires.

FIG. 32 is a partial side elevational view of an alternate embodiment ofan expandable sheath tube incorporating a wire having a circular distalend.

FIG. 33 is a partial side elevational view of an alternate embodiment ofan expandable sheath tube incorporating an expandable wire including twohalf-circles at the distal end of the sheath tube.

FIG. 34 is a partial side elevational view of an alternate embodiment ofan expandable sheath tube incorporating expandable wires forming a "W"pattern at the distal end of the sheath tube.

FIG. 35 is a side elevational view of a sheath assembly inserted into avessel, wherein an introducer capsule is being removed from the sheathtube.

FIG. 36 is a side elevational view of a sheath assembly inserted in avessel wherein a removable capsule is being used to withdraw the sheathtube from the vessel.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In general, the large-diameter expandable sheath is used forintroduction of a catheter into the body of a patient. It comprises anelongate sheath tube formed of a flexible material and having proximaland distal extremities and having passage therein of a predeterminedmaximum diameter. The distal extremity of the elongate sheath tube isfolded longitudinally into a smaller diameter. A backflow adapter issecured to the proximal extremity of the elongate sheath tube. Thebackflow adapter has a central opening therein in registration with thepassage in the sheath tube. Valve means is disposed in the centralopening in the backflow adapter and is movable between open and closedpositions. The valve means when in an open position permits a catheterto be introduced into the sheath and when closed forms a liquid-tightseal about the catheter extending therethrough.

More particularly as shown in FIG. 1 of the drawings, the large-diameterexpandable sheath 11 consists of an elongate sheath tube 12 havingproximal and distal extremities 13 and 14 and having a flow passage 16having a maximum diameter extending therethrough. The expandable sheath11 can have a suitable length as, for example, fifteen to thirty-fivecentimeters and preferably approximately eighteen centimeters with amaximum outside diameter of one centimeter. The elongate sheath tube isformed of a flexible material having a wall thickness of 0.001 to 0.020inches (0.0254-0.51 millimeters) and preferably about 0.005 inches(0.127 millimeters) and can be formed of a suitable plastic materialsuch as "TEFLON" (a fluorinated ethylene propylene). An alternatematerial is "TEFZEL" (ethylene tetrafluoroethylene). The selectedmaterial should have physical characteristics which will not becompromised by radiation sterilization.

As shown in FIG. 4, the distal extremity of the sheath tube is pleatedor folded longitudinally to provide wraps or folds 17 for a distance ofapproximately ten centimeters from the distal end to provide a distalextremity of reduced diameter as, for example, a reduction of theoutside diameter from 3/8 to 3/16 of an inch (9.52-4.76 millimeters) orapproximately one-half the original size. The folding or pleating of thesheath tube 12 in this manner serves two purposes. The first purpose isto reduce the sheath diameter to facilitate introduction of the sheathand to make it less traumatic for the vessel into which it isintroduced. The second reason is that with a small-diameter, thin-walltube, as represented by the elongate sheath tube 12, there is lesslikelihood of kinking occurring than in a large-diameter, thin-walltube. The distal extremity of the sheath tube 12, when foldedlongitudinally in this manner, serves to provide kink resistance in thedistal extremity 14 while still being relatively flexible.

If it is desired to further decrease the likelihood of kinking in thelarge-diameter, thin-wall tube which forms the sheath tube 12, anotherembodiment of the sheath tube can be provided of the type shown in FIGS.5, 6 and 7. The sheath tube 18 shown in those figures is provided with aplurality of circumferentially spaced apart flexible elongate elements19 which are embedded in the wall of the tube 18 and extendlongitudinally along the length thereof as shown in FIG. 5. The proximalextremities are offset or staggered as shown in FIG. 5 with alternateelements 19 being shorter. This offset relationship provides a gradationin stiffness in the proximal extremity of the sheath tube 18. Theelongate elements 19 can be in the form of stainless steel wires havinga diameter ranging from 0.005 to 0.015 inches (0.127-0.381 millimeters)and preferably a diameter of approximately 0.010 inches (0.254millimeters). As can be seen from FIG. 6, the sheath tube 18 can bulgeoutwardly around the elongate elements 19 while being relatively thinbetween the elongate elements to retain the flexibility of the tube 18.As also can be seen from FIG. 6, the elongate elements 19 are spacedapart in the three groups to facilitate the formation of six folds 20 asshown in FIG. 7. Thus, by way of example, each set of elongate elementscan have the elongate elements spaced approximately 35° apart with eachset being spaced approximately 85° apart. Spacing of the elongateelements 19 in this manner facilitates the formation of the folds shownin FIG. 7. The elongate elements 19 also provide additional rigiditylongitudinally of the tube 18 so as to inhibit accordioning of the tube18 during removal of the introducer as hereinafter described.

As shown in FIG. 22, sheath tube 12 may be provided with a sheath marker180 located at the distal end 14 of the sheath tube. The sheath markeris formed of a radiopaque alloy, for example platinum-tungsten orplatinum-iridium. The sheath marker is molded inside the distalextremity of the sheath tube to enable the physician to locate thesheath tip during the operative procedure. A laminating patch is createdfrom a tab of sheath material located at the distal tip of the sheath.This tab is folded back over and fused to the sheath tip to laminate theradio opaque marker on the inside tip of the sheath tube. Thus, themarker resides between two laminated layers of the sheath tube. As shownin FIG. 23, the distal end of the sheath tube may be folded into fourbifolds 181 to form a square-like configuration, wherein the sheathmarker is embedded within one of the sides 182 of the folded square.

A backflow adapter 21 is secured to the proximal extremity of theelongate sheath tube 12. The backflow adapter 21 consists of a housingor body 22 which is formed of a suitable material, for example, aplastic such as polycarbonate. The housing 22 is provided with a centralbore 23 extending therethrough in axial alignment with the passage 16 ofthe sheath tube 12. A cylindrical sheath tube adapter 26 is disposed inthe bore 23 and is provided with an annular recess 27 which receives aninwardly-extending flange 28 provided on the proximal extremity 13 ofthe sheath tube 12 (see FIG. 8). A tubular insert 29 formed of the samematerial as the sheath tube 12 but of a greater wall thickness, as forexample twice the wall thickness of the sheath tube 12, is securedwithin an annular recess 30 in the sheath tube adapter 26 by suitablemeans such as an adhesive. The insert 29 serves as a reinforcement andserves to prevent collapse of the proximal extremities 13 of the sheathtube 12 when the expandable sheath 11 is used. The sheath tube adapter26 is fixed within a first cylindrical collar 31 seated within the bore23 and is held in place by solvent bonding the cylindrical collar 31into the housing or body 22 to prevent longitudinal and/or rotationalmovement of the first collar 31 relative to the housing or body 22. Asecond collar 34 is also seated in the bore 23 and is rotatable therein.An annular ring gear 36 having teeth 36 thereon is also rotatablymounted in the bore 23 as hereinafter described.

A cylindrical or tubular valve member or diaphragm 40 is disposedbetween the first and second collars 31 and 34, and is provided with abore or flow passage 41 extending therethrough. The valve member 40 isprovided with inwardly extending annular lips or flanges 42 and 43provided on opposite extremities of the same (see FIGS. 8 and 14). Theflange 43 is seated in an annular recess 46 in the sheath tube adapter26 and is retained therein by the first collar 31. The flange 42 isseated in an annular recess 47 provided in a retaining ring 48 andretained therein by the second collar 34. An annular protrusion 49 isformed integral with the retaining ring 48 and engages one side of thetoothed ring gear 37 which is secured to the retaining ring 48 bysuitable means such as an adhesive. Similarly, the retaining ring 48functionally engages the second collar 34 and causes the second collar34 to rotate therewith.

The diaphragm or valve member 40 can have a suitable size as, forexample, a length of 0.3 to 0.45 inches (7.62-11.43 millimeters) andpreferably a length of approximately 0.3 inches (7.62 millimeters), andan inside diameter of 0.35 to 0.5 inches (8.89-12.7 millimeters), andpreferably an inside diameter of 0.375 inches (9.52 millimeters), with awall thickness ranging from 0.005 to 0.015 inches (0.127-0.381millimeters), and preferably a wall thickness of 0.007 inches (0.178millimeters). The annular lips 42 and 43 can extend inwardly for adistance of 0.032 inches (0.813 millimeters) from the outer wall surfaceand have a length of approximately 0.050 inches (1.27 millimeters). Thediaphragm or valve member 40 can be formed of a suitable material, suchas a silicone elastomer, as, for example, Dow "SILASTIC" 97-4720. It canhave a Shore A hardness ranging from 20-80 and preferably a Shorehardness of 40A. Alternatively, a low durometer, tear-resistantrubber-like latex material can be utilized.

Other diaphragm or valve members such as shown in FIGS. 15 and 16 can beutilized which have the same physical conformation. In the embodimentshown in FIG. 15, small diener polyester fibers 52 are bonded to theexterior surface of the diaphragm 51 with a silicone adhesive so thatthe fibers 52 extend circumferentially around the outside surface of thediaphragm 51. Such fibers serve to impede radial and longitudinaldistention of the diaphragm or valve member 51. The diaphragm or valvemember 56 shown in FIG. 16 is provided with a cylindrical wall 57 whichincreases in thickness in a direction towards the distal extremity ofthe diaphragm. This helps the diaphragm to withstand the pressuresapplied to the diaphragm during use, which may cause the diaphragm todistend and leak. Means is provided for causing relative rotationbetween the sheath tube adapter 26 and the retaining ring 48 for openingand closing the bore or flow passage 41 by twisting of the cylindricalvalve member or diaphragm 40 (FIG. 9). This is accomplished by fixingthe first collar 31 and the sheath tube adapter 26 within the housing orbody 22 by suitable means such as solvent bonding and causing rotationof the retaining ring 48 by the use of a rack 61. The rack 61 consistsof a rod 62 formed of a suitable material such as stainless steel whichextends through a hole 63 (see FIG. 11) in the housing or body 22 in adirection which is tangential of the bore 23. The rod 62 is disposedimmediately adjacent a flange 1 formed in the body 22 against which thering gear 36 rotates. The hole 63 opens into the bore 23 so that rackteeth 64 provided on the one side of the rod 62 engage the toothed ringgear 36 whereby upon reciprocatory movement of the rack 61, the ringgear 36 is rotated through an angle ranging from 180° to 360°, andpreferably an angle of at least 270°.

An actuator 66 formed of a suitable material such as plastic is mountedon the upper extremity of the rod 62 and is secured thereto by suitablemeans such as an Allen-head screw 67 set into the rod 62, as shown inFIG. 13. The actuator 66 is generally rectangular in plan and isprovided with an upstanding lip 68 so that it conforms to theconformation of the index finger of the hand which is to be utilized foractuating the rack 61. The actuator 66 is provided with a reinforcingrib 69 along one edge of the same. A similar actuator member 71 isprovided on the body 22 underlying the actuator 66 and is also providedwith a downwardly extending lip 72. The actuator member 71 is secured tothe body 22 by suitable means such as an adhesive. The member 71 alsohas a rectangular configuration in plan and is sized so that it isadapted to be engaged by the thumb of the hand, as shown in FIG. 12.Thus, one hand can be utilized for operating the backflow adapter 21 bythe index finger of the hand grasping the actuator 66 and the thumb ofthe same hand grasping the member 71.

A stabilization and guide rod 76 extends through a tangential bore 77(see FIG. 11) provided in the body 22 which is spaced apart from thebore 63 and extends in a direction which is parallel thereto. The rod 76is formed of a material such as stainless steel and is provided with acollar 78 which extends through the reinforcing rib 69 of the actuator66 and is secured therein by suitable means such as an Allen-head screw79.

In an alternative embodiment of the normally closed primary valve ifshown in FIGS. 24 and 25, the actuator 66 is turned 90° so that guidestabilizer rod 76 is positioned on the opposite side of the proximalvalve housing 22 to the rack 62. A ring gear 161 is configured into agear hub 160 which causes rotation of proximal diaphragm retaining ring158. The distal end of the primary diaphragm 40 is secured to the distalretaining ring 159 which is fixed relative to the proximal valve housingand is positioned proximal a distal retaining hub 162. The primarydiaphragm is opened by depressing the actuator which causes the rack tomove the ring gear and rotate the gear hub and proximal retaining ring.In addition, a cover 170 is added to the bottom of the body to encasethe bottom portions of the rack and stabilizer rod. Also, a "C"-shapedkeeper 171 can be used to maintain the actuator in the compressed oropen valve position by placing one end over the actuator and the otherend over bottom of the cover.

Referring to FIG. 11, means is provided for yieldably returning the rack61 into a position so that the valve member or diaphragm 40 is in anormally closed position and consists of a coil spring 81 coaxiallymounted on the rod 62 and having one end engaging the actuator 66 andhaving the other end engaging a seat 82 provided in the body 22. Meansis provided for preventing the spring 81 from urging the rod 62 out ofthe bore 63 and consists of a lump 83 of solder or a braising materialprovided on the rod 62 adjacent the lower extremity of the rack teeth64. Thus, it can be seen by the hand engaging the backflow adapter 21using the index finger to engage the actuator 66 and the thumb to engagethe actuator member 71, the rack 61 can be reciprocated back and forthto open and close a bore 86 extending through the retaining ring 48 andthe sheath tube adapter 26 by forming an hourglass or iris-like closureas shown in FIG. 9 in which the radially extending lines 87 shownrepresents the folding over of the elastomeric material of the valvemember or diaphragm 40. The collar 78 provided on the stabilization rod76 serves to stop further travel up the rack when the collar 78 engage aseat 88 provided in the body 22. In this position, the spring 81 isalmost completely compressed as shown in FIG. 10. Following the releaseof the actuator 66, the spring 81 returns the rack 62 to its homeposition and causes the valve member or diaphragm 40 to be completelyclosed as shown in FIG. 9.

The ring gear 36 can be formed of a suitable material such as stainlesssteel and can have any suitable number of teeth. Alternatively, the ringgear can be formed of a suitable plastic such as nylon. The otherportions of the backflow adapter 21 as, for example, the body 22, thefirst collar 31, the second collar 34, the retaining ring 48 can beformed of a suitable plastic such as polycarbonate. The metal parts suchas the rod 62, the stabilization rod 76 and the spring 81 can be formedof a suitable material such as stainless steel.

As shown in FIGS. 1 and 8, means is provided for introducing liquid as,for example, a radiopaque liquid, into the bore 86 and consists of atube 91 formed of a suitable material such as plastic extending throughthe first collar 31 and through the sheath tube adapter 26 so that it isin communication with the bore 86. Flexible tubing 92 is connected tothe tube 91 and has a stopcock 93 of a conventional type mounted thereonwhich is provided with a Luer-type fitting 94. The stopcock 93 isprovided with a knob 96 which can be utilized for moving the stopcock 93between open and closed positions.

As shown in FIGS. 20-21, an alternate embodiment of the sheath assembly11 includes a normally open secondary valve assembly 150 locatedadjacent the primary valve housing 22 of the backflow adapter 21. Thesecondary valve assembly contains a secondary diagram 151 which operatessubstantially the same as the primary diaphragm 40 and is actuated by athumb wheel 152. The secondary diaphragm is made of silicone and isconstructed substantially the same as the primary diaphragm. Thesecondary diaphragm is configured to have a suitable length, diameterand wall thickness to be compatible with the primary diaphragm.Similarly, each of the materials used in the secondary valve assemblyfor constructing and mounting the secondary diaphragm are substantiallythe same as the materials previously described for the backflow adapterassembly.

The primary valve assembly is configured similar to that described abovein conjunction with FIGS. 24 and 25. Secondary valve housing 155 isprovided with a central bore 165 which is in fluid communication withthe central bore 23 of the primary valve housing 22 and the passage 16of the sheath tube 12. Likewise, secondary diaphragm or valve member 151is provided with a flow passage extending therethrough. Thus, aninstrument such as the sheath introducer 101 may be passed through theprimary diaphragm when the secondary diaphragm is closed, therebypreventing blood flow through the proximal end of the large-diameterexpandable sheath assembly 11. Also, orifice 163 in the valve housingand orifice 164 in the sheath tube adapter 26 are provided to accepttube 91 connected to the flexible tubing 92 of a introducer sideportassembly (not shown).

As shown in FIG. 21, the secondary valve assembly 150 comprises asecondary valve housing 155 which contains secondary diaphragm 151 andthumb wheel 152. The proximal end of the secondary diaphragm is securedto the thumb wheel by proximal retaining ring 156. The distal end of thesecondary diaphragm is fixed relative to the secondary valve housing bydistal retaining ring 157. Rotation of the diaphragm is achieved byrotating the thumb wheel so as to cause motion to only the proximal endof the secondary diaphragm. A rotational stop (not shown) is positionedon the thumb wheel to prevent excess rotation of the secondarydiaphragm. The rotational stop may be comprised of two 1/32 of an inch(0.79 millimeters) dowel pins located on the thumb wheel and thesecondary valve housing which are configured to engage each other tolimit the rotation of the thumb wheel. Additionally, a silicone o-ring153 positioned proximate the thumb wheel in the primary diaphragm distalretaining hub 162 allows rotation of the thumb wheel while preventingfluid from leaking from the backflow adapter housing.

A sheath introducer 101 is provided as a part of the assembly shown inFIG. 1 and as shown in FIG. 2 consists of an elongate tubular member 102formed in three sections 103, 104 and 106 of different diameters. Theelongate tubular member 102 can be formed of a suitable plastic materialsuch as "PEBAX" which is formed of polyether Block hides which is loadedwith approximately 10% barium sulfate to make the same visible underX-rays. Section 103 can have a diameter ranging from 0.15 to 0.3 inches(3.81-7.62 millimeters) and preferably an outside diameter of 3/16 of aninch (4.75 millimeters). The section 104 can have a suitable diameteras, for example, 0.08 to 0.15 inches (2.03-3.81 millimeters) andpreferably a diameter of 1/8 of an inch (3.17 millimeters). The section106 can have a diameter ranging from 0.06 to 0.12 inches (1.52-3.05millimeters) and preferably a diameter of 0.08 inches (2.03millimeters). The distal extremities of the sections 103 and 104 areprovided with tapers 107 and 108, respectively, so as to provide atapered transition from one diameter to another. A Luer-type fitting 111is mounted on the proximal extremity of the tubular section 103. A boreor lumen 112 (see FIG. 4) of a suitable size as, for example, onecapable of passing a 0.038 inches (0.97 millimeters) guidewire, isprovided in the section 106 as well as in the sections 104 and 103extending the length of the tubular member 102.

As shown in FIG. 3, a tube 116 is mounted on the distal extremity 106 ofthe sheath introducer 101 and is formed of a suitable material such assilicone and is retained thereon in a suitable matter by the use ofpolyethylene shrink tubing 117. A cylindrical enlargement or annularbump 121 is provided on the tubular section 106 adjacent the distalextremity of the shrink tubing 117 and serves to prevent the sleeve 116and the shrink tubing 117 from accidentally slipping off of the distalextremity of the tubular section 106.

When the sheath introducer 101 is disposed in the expandable sheath 11,as shown in FIG. 1, the proximal extremity of the silicone sleeve 116 isdisposed over the distal extremity of the sheath tube-12 and serves toprevent the sharp edges of the folded sheath tube 12 from causing traumato the interior wall of a vessel when it is introduced into the vesselwhen the sheath is introduced as hereinafter described. A vent hole 123is provided in the sheath introducer 101 which is in communication withthe passage 112 proximal of the silicone sleeve 116, as shown in FIG. 3.The vent hole 123 can be utilized for flushing the elongate sheath tube12 through the side port fitting 94 prior to use of the expandablesheath in a surgical procedure. As shown in FIG. 26, a radiopaque markerband 185 may be positioned proximal to distal end of the sheathintroducer 101. The marker band is made of a radiopaque alloy,platinum-tungsten or platinum-iridium. The marker band is positionedjust proximal the retaining bump 121 over the elongate tubular member102 and within silicone sleeve 116 and polyethylene shrink tubing 117.The platinum alloy band is held in place by both the silicone sleeve andthe polyethylene shrink tubing. As appropriate, the marker band may bepositioned elsewhere along the length of the sheath introducer, such aswithin the most distal tubular section 106.

Operation and use of the expandable sheath 11 in conjunction with thesheath introducer 101 may now be briefly described as follows. Let it beassumed that the patient has been prepared in a conventional manner andthat it is desired to enter a peripheral vessel such as an artery or avein of the patient. The desired vessel is exposed and a longitudinal ortransverse incision made into that vessel. A guidewire of a suitablesize is then selected as, for example, a guidewire having a diameter of0.038 inches (0.97 millimeters). The guidewire (not shown) is introducedinto the vessel and then the expandable sheath assembly 11 shown in FIG.1 is placed over the guidewire by placing the proximal extremity of theguidewire into the lumen 12 provided in the elongate tubular member 102and advanced through the Luer fitting 111. The rounded tip and the smalldiameter of the section 106 of the tubular member 102 facilitateadvancement of the sheath introducer 101 into the vessel withouttraumatizing the vessel. The small-diameter tip section 106 is followedby the elongate sheath tube 12 which has been collapsed as hereinbeforedescribed about the tubular section 106 until the sheath tube 12 hasbeen introduced to the proper depth in the vessel. As soon as the sheathtube 12 has been positioned in the vessel, the sheath introducer 101 isadvanced relative to the elongate sheath tube 12 by using one hand tohold the backflow adapter 21 which is connected to the sheath tube 12and the other hand to push the sheath introducer 101 so that theproximal extremity of the silicone sleeve 116 moves off of the distalextremity of the sheath tube 12 to expose the same.

As soon as this has been accomplished, the sheath introducer 101 ispushed forward so that section 103 enters the collapsed section of thesheath tube 12 to commence opening of the same. The sheath introducer101 is then removed through the backflow adapter 21. The sheathintroducer can be removed by grasping the backflow adapter 21 by thefingers of the hand as hereinafter described to at least partially openthe same to permit removal of the sheath introducer and dilator 101while minimizing the flow of blood from the sheath tube 12. The backflowadapter can then be released. The sheath 11 and its backflow adapter isnow in its normally closed state to provide a hemostatic seal closingthe flow passage 86.

The physician conducting the procedure then selects the desired catheteror other device which is desired to be introduced through the expandablesheath 11. Such a device should have a diameter of 8.5 millimeters orless or which is at least slightly less than the diameter of the bore86. The physician grasps the actuator members 66 and 71 and presses thesame to operate the rack 61 to open the diaphragm or valve member 40permitting the physician to insert the device as, for example, thecatheter through the expandable sheath 11. As soon as the catheter hasbeen advanced as far as desired, the physician releases the pressure onthe actuator members 66 and 71 permitting the diaphragm 40 to closearound the device as, for example, the catheter inserted through to forma hemostatic seal about the catheter. If it is desired to reposition thecatheter, it is merely necessary to push or pull the catheter and itwill slide freely through the diaphragm. When it is desired to removethe catheter, the catheter need only be pulled out of the sheath 101 andthe diaphragm will seal closed forming a hemostatic seal.

A silicone coating may be applied to the pleated sheath tube 12. Coatingmay be applied to the inner and outer surfaces prior to attachment tothe backflow adapter 21. The silicone coating on the inside diameter ofthe sheath tube reduces the amount of force required to advancecatheters and the like through the sheath tube. Additionally, thesilicone coating on the outside of the sheath tube may reduce the amountof force required to advance the expandable sheath 11 into a vessel. Asuitable silicone coating material is "HYDRO-SIL-D 1.0" available fromTUA systems of Sarasota, Fla. Additionally, a silicone lubricant may beapplied to the ring gear 36 on the primary valve assembly and theadjacent to bearing surfaces.

The method for introducing a medical instrument into the body of apatient using the dual valve expandable sheath assembly 11 shown inFIGS. 21-26 involves opening the valves to minimize blood flow throughthe sheath assembly 11. First, the sheath introducer 101 is placedwithin the sheath assembly such that the distal end 14 of the sheathtube 12 resides in the introducer sleeve 116, as shown in FIG. 26. Thisstep may be performed as part of the manufacturing process. After thepatient is prepared for the procedure, the sheath tube and the sheathintroducer are intraluminally inserted into the patient, usually througha cutdown in a vessel such as a femoral artery. The distal end 106 ofthe sheath introducer is then inserted into the vessel until the distalend of the sheath tube is within the vessel. The sheath introducer isthen advanced into the vessel relative to the sheath tube, allowing thedistal end of the sheath tube to expand. In addition, the sheathintroducer may be further advanced into the sheath assembly to dilatethe distal end of the sheath tube.

Next, the sheath introducer 101 is removed from the sheath assembly 11.As the distal end 106 of the sheath introducer is removed from thesheath tube 12, the secondary valve 151 is closed to form asubstantially fluid tight seal between the passage 16 in the sheath tubeand the secondary valve assembly 150. After the secondary diaphragm 151is closed, the primary diaphragm. 40 may be opened to fully remove thesheath introducer. Then the distal end of a catheter or other medicalinstrument may be inserted through the primary valve. The primarydiaphragm is then closed to form a substantially fluid tight seal aroundthe medical instrument. Next, the secondary diaphragm is opened to allowthe distal end of the medical instrument to be inserted through thesecondary valve assembly, through the passage in the sheath tube andinto the vessel of the patient. After the procedure has been completed,the medical instrument and the sheath assembly can be removed from thevessel and the incision which has been made in the vessel for permittingpassage of the sheath assembly can be sutured.

It can be seen from the foregoing that there has been provided anexpandable sheath 11 which can be made in various sizes to accommodatelarge-diameter devices while still providing the desired hemostaticseal. The expandable sheath can be readily inserted and removed. Thesheath introducer 101 facilitates this introduction. It is provided witha distal extremity 106 which is small in diameter to permit the sheathtube 12 to be wrapped about the same as hereinbefore described. Thesheath introducer 101 is provided with sections 103 and 104 of largerdiameters to provide additional rigidity to the sheath introducer 101 tofacilitate pushing of the sheath introducer when introducing theexpandable sheath 11 into the vessel of the patient.

An alternative mechanism for actuating the diaphragm 40 is shown in FIG.17 and consists of a pinion 131 which engages the ring gear 36 and isdisposed in a cylindrical recess 132 provided in the body 22. The pinion131 is mounted on a shaft 133. Another gear 134 is mounted on the shaft133 and has a smaller diameter than the diameter of the pinion 131 andengages the rack teeth 64 provided on the rod 62. By providing such agear arrangement, it can be seen that it is possible to provide ashorter rack to achieve the same degree of ring gear rotation foropening and closing of the diaphragm 40.

As can be seen in FIGS. 18 and 19, there is shown another embodiment ofa mechanism for actuating the diaphragm 40. As shown therein it consistsof a flexible rack 141 that is comprised of a flexible member 142 whichis provided with rack teeth 143 on one side of the same which areadaptable to engage the ring gear 36. The member 142 extends through asemicircular slot 144 provided in the body so that it extends throughthe body and around the ring gear 36. An actuator 146 is provided formedintegral with the rack 141 for operating the rack 141 with the fingersof the hand. In this construction the rack is substantially containedwithin the body 22.

As shown in FIGS. 27-36, the expandable sheath 11 may include areinforced sheath tube 200. The reinforced sheath tube is similar to theelongate sheath tube 12 and similarly has proximal and distalextremities 201 and 202. A flow passage 203 is provided having a maximumdiameter extending therethrough. One suitable material for thereinforced sheath is in an expanded PTFE (polytetrafluoroethylene). Suchmaterials may be obtained from Impra of Temp, Arz., and W. L. Gore ofFlagstaff, Arz. An example of a suitable size for a sheath tube for usewith large catheter systems would include an outer diameter ofapproximately 0.345 inches (8.76 millimeters) with a wall thickness of0.005 inches (0.127 millimeters) and having a length of about twentycentimeters.

The reinforced sheath tube 200 could be supported by stents, coiledwire, coiled plastic or similar means. As shown in FIG. 27, a series ofself-expanding supports 210 may be placed within the sheath tube forradial expansion. The wire, as shown, is sinusoidal in shape. Similarly,as shown in FIG. 28, a coil 211 may be attached to the outside of thesheath tube to allow for self-expansion. Alternatively, the coil supportmay be embedded within an inner sheath tube 212 and outer sheath tube213, as shown in FIG. 29. The coil or expansion system may be made of a0.012 inches (0.3 millimeters) nitinol or similar alloy wire. As shownin FIG. 30, the reinforced sheath may include balloon expandable stents214 which may be expanded by a balloon 215 and catheter 216 or similarmeans.

Alternatively, the sheath tube 200 may be made of a dacron graft 217supported by longitudinally positioned nitinol wires 218 as shown inFIGS. 31-34. As shown in FIG. 31, the reinforcement wires may be run astightly parallel U-shaped expansion means. Likewise, a single wireforming a circle at the distal end 202 of the sheath tube may be used.Similarly, two wires forming half-circles at the distal end may be usedto reinforce and expand the sheath as shown in FIG. 33. Alternatively,the wires may form a "W" or sinusoidal shape at the distal end of thesheath tube to provide radial expansion, as shown in FIG. 34.

As shown in FIG. 35, the large-diameter expandable sheath assembly 11includes an introducer capsule 220. The reinforced sheath tube 200 ispacked into the introducer capsule for deployment. The introducercapsule has a significantly less inner diameter than the outer diameterof the expanded sheath tube. The introducer capsule is configured suchthat it will peel away from the proximal end 201 of the reinforcedsheath tube as the introducer capsule is withdrawn from the distal end202 of the sheath tube. As the sheath introducer capsule is withdrawn,the reinforced sheath tube expands radially within the vessel.

As shown in FIG. 36, a removal capsule 225 may be fitted around theproximal 201 end of the reinforced sheath tube 200 to collapse theexpanded sheath tube after the sheath tube has been deployed in avessel. The removal capsule is configured with a lengthwise slit so itmay be fitted over the proximal end of the secondary valve withouthaving to fit over the backflow adapter 21. The removal capsule outerdiameter is less than the outer diameter of the expanded sheath tube soas to radial collapse the sheath tube to a smaller diameter state. Oncethe reinforced sheath tube is collapsed, the removal capsule and sheathtube are then removed from the vessel. This retrieval reduces potentialvessel trauma from removing a large diameter sheath.

While several particular forms of the invention have been illustratedand described, it will be apparent that various modifications can bemade without departing from the spirit and scope of the invention. Forexample, references to materials of construction and specific dimensionsare also not intended to be limiting in any manner and other materialsand dimensions could be substituted and remain within the spirit andscope of the invention. Accordingly, it is not intended that theinvention be limited, except as by the appended claims.

What is claimed is:
 1. An expandable sheath for use in introducing amedical instrument into a body, the sheath comprising:an elongate sheathtube having proximal and distal ends having an annular passagetherethrough, said elongate sheath tube being formed of a flexiblematerial; and a self-expanding wire associated with the wall of saidelongate sheath tube for causing radial expansion of said sheath tube toexpand the annular passage such that a medical instrument can beinserted into the passage.
 2. The expandable sheath of claim 1, whereinthe self-expanding wire of said reinforcing means is sinusoidal inconfiguration.
 3. The expandable sheath of claim 1, wherein theself-expanding wire of said reinforcing means is helical inconfiguration.
 4. The expandable sheath of claim 1, wherein theself-expanding wire of said reinforcing means is configured totransverse a length of said sheath tube and to encircle the perimeter ofthe distal end of said sheath tube.
 5. The expandable sheath of claim 1,wherein the self-expanding wire of said reinforcing means is configuredto transverse the length of said sheath tube and to form a sinusoidalshape along the perimeter of the distal end of said sheath tube.